About Optics & Photonics TopicsOSA Publishing developed the Optics and Photonics Topics to help organize its diverse content more accurately by topic area. This topic browser contains over 2400 terms and is organized in a three-level hierarchy. Read more.

Topics can be refined further in the search results. The Topic facet will reveal the high-level topics associated with the articles returned in the search results.

Abstract

A systematic method is proposed for designing an optical system for road lighting using an LED and a freeform lens that is optimized to produce a certain luminance distribution on the road surface. The proposed design method takes account of the luminance characteristics of the road surface, the energy efficiency of the system, the glare problem of the luminaire and the effects of four adjacent luminaries illuminating a single road surface. Firstly, the road surface illuminance with a polynomial of cosine functions along the road is optimized to maximize Q (the ratio of the average luminance to the average illuminance) as well as satisfying the lighting requirements provided by CIE. Then, a smooth freeform lens with this optimized illuminance is designed based on the variable separation method and the feedback modification method. Results show that, from two typical observer positions on the 2-lane C2 class road, luminaires with these freeform lenses can provide Q values of 7.90 × 10−2 and 8.69 × 10−2, the overall road surface luminance uniformity of 0.55 and 0.56, the longitudinal road surface luminance uniformity of 0.72 and 0.79, and the glare factors of 10.06% and 6.73% .

Figures (12)

Luminance distributions produced by luminaires with uniform illuminance. The mounting space S = 35m, mounting height H = 10m, road width W = 7.5m, and the observer position is (−60m, 1.875m, 1.5m). The maximum lighting range along the road of each luminaire is (a) 17.5m or (b) 35m, and the luminance distributions produced by luminaires with these two uniform illuminance distributions are shown in (c) and (d), respectively.

Comparison of lighting parameters produced by luminaires1 (LP1), lumiaires2 (LP2), and luminaires3 (LP3) with the observer’s position at (a) (−60m, 1.875m, 1.5m) and (b) (−60m, 5.625m, 1.5m). Q0 (0.07) is the average luminance coefficient for C2 road

(a). The original lens model with an LED source. (b).Light distribution curves derived from the simulation results of the original lens and the optimized illuminance distribution. The flux is unified into 1000lm

(a). The final lens model after six times feedback with an LED source. (b). Light distribution curves derived from the simulation results of the final lens and the optimized illuminance distribution. The flux is unified into 1000lm